To obtain preliminary data on the potential influence of Tamoxifen, an "anti-estrogen," on brain chemistry and on neuropsychologic testing,. Tamoxifen is currently used for the adjunctive therapy of breast cancer, and may soon also be recommended for breast cancer prevention. Since estrogen replacement therapy reduces the risk for Alzheimer Disease, i.e. estrogen may be neuroprotective, there is a risk that the "anti-estrogen" Tamoxifen might increase risk for dementia.